* This high-tech security alarm transforms an ordinary doorknob into a highly sensitive burglar alarm. * In order to gain easy access to your home burglars will first try your doors to see if they are unlocked. * If a burglar touches your outside doorknob this device will instantly emit a loud alarm to scare him away and alert you to the attempted entry. * Unlike other alarms, the burglar will be stopped before he enters your home. * Even if he is wearing gloves, the alarm will sound as soon as the outside doorknob is touched. * No installation required: simply hang on the inside doorknob of any wooden door. * Please note that this alarm will only work on wooden doors. * Requires one 9 volt battery (not included) * Alarm on/off switch * LED power indicator * 20cm string * Unit dimension: 95 x 45 x 21mm * Unit weight: 70g